1. Field of the Invention
The present invention relates, generally, to means for suppressing infrared radiation emanating from an aircraft, more particularly to infrared radiation filter lenses for suppressing such radiation, and most especially to such filter lenses for suppressing the infrared radiation otherwise emitted from aircraft lights such as landing lights and taxi lights.
2. The Problem to be Solved
Modern aircraft have myriad sources of infrared radiation; i.e., devices which, in operation, emit radiation extending into the infrared portion of the spectrum. The principal infrared sources are lights and the aircraft engines themselves. Many weapon systems are designed to take advantage of these characteristics; the so-called "heat seeking" missiles tracking hot spots on an aircraft by homing in the infrared portion of the spectrum during flight. From an aft aspect, the engines present a principal infrared radiation source for tracking, whereas the forward aspect features more prominently the aircraft lights such as the taxi and landing lights.
Very complex electronic countermeasure devices have been developed with an eye toward neutralizing the ability to home on the infrared sources in an aircraft. As might be expected, the complexity of these sophisticated systems gives rise to a significant cost factor. As respects the need to protect the aircraft against a successful attack, these costs are justifiable given the current state of the art in relation to the infrared radiation emitted from engine sources. The need to find other viable approaches respecting the suppression of infrared radiation from aircraft lights, with an eye toward a less costly solution, led to the development of the instant invention--one employing radiation filters.